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Evaluation of Biochemical Clogging of Filters and Emitters on Microirrigation Scheduling

Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan www.asabe.org

Citation:  2007 ASAE Annual Meeting  072201.(doi:10.13031/2013.22983)
Authors:   Yamamoto Tahei , Bouya Ahmed Ould Ahmed , Andry Henintsoa , Tanaka Satoshi , Fujiyama Hideyasu , Miyamoto Koichi
Keywords:   Emitter clogging, Clogging fraction, Microirrigation scheduling model

To assess biological and chemical clogging of filters and emitters in a microirrigation system, monitoring studies have been conducted since 1990 in the Tohaku National Irrigation Project (TNIP), Japan. The soils in the region are fertile volcanic ash and intensive livestock industry in the river basin of the TNIP. These conditions provided favorable conditions for contamination of water and growth of planktons, shells and other organisms in farm ponds and reservoirs. Farmer in the project area uses two types of microirrigation emitters. Namely, these are a micro showering type emitter Semi-shower (SS) and a mist spraying type emitter Semi-tube (ST). The SS is primarily used by vegetable growers, and for lawn and orchards in open fields, whereas the ST mostly for vegetables in greenhouses. Irrigation scheduling for the two types of micro-emitters is discussed using simulation models and experimental data collected in the field. An equation for improved water requirement (IW) is introduced embedding a biological clogging fraction (CF) and net water requirement without clogging (NW) as follows; IW = NW (1 - CF)-1. Using the historical daily rainfall data for the last 15 ~ 30 years, the IW calculated for the SS emitter for 10 day irrigation intervals increased by 50 ~ 100 % at CF = 0.5 compared with CF = 0.0. However, in the daily irrigated open field condition, there was no significant difference in IW between CF = 0.0 and CF = 0.5 and this is attributed to irregular water distribution due to emitter clogging covered by effective rainfall. Thus, frequent microirrigation is recommended as the appropriate practice to improve irrigation efficiencies when biological emitter clogging is an issue that reduces efficiencies of the system. The results indicate the most efficient use of rainfall resource stored in the root-zone by crops during the growing season under microirrigation system use.

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